A week ago at Youth & Opportunity United (Y.O.U.) summer camp, I made pancakes with a group of middle school campers. The goal was to eat good food and learn something about the scientific method and the science of food. We had a basic pancake recipe, which we made and enjoyed, but the pancakes were quite flat. We all craved fluffy, light pancakes, so we set out to make it happen by altering the amount of baking powder in the batter and subjectively rating the fluffiness.
As we conducted the experiment, it became apparent that our hypothesis was correct: increasing the ratio of baking powder to other ingredients did make the pancakes fluffier. During the experiment I wondered, what exactly is baking powder? Why does it make the pancakes fluffy? How is it different from baking soda? I had used baking powder and soda in recipes all my life, but had never considered their part in the baking process.
Leavening, the process of making dough rise, is generally accomplished in three ways: with baking soda, baking powder (which contains baking soda), or yeast. Baking soda (sodium bicarbonate) is a base, the chemical counterpart to an acid. In most cases, acids and bases are very reactive and react especially quickly with each other. In cooking, the acids most commonly used to create reactions with baking soda are lemon or lime juice, vinegar, buttermilk, honey, coffee or cocoa. This is what happened in fourth grade science fair volcanoes when baking soda was combined with vinegar to spit foam everywhere.
On the other hand, baking powder is a combination of baking soda and two powdered acids, meaning you don't have to add your own. The two are monocalcium phosphate, which reacts with the baking soda as soon as a liquid is added to it, and sodium aluminum sulfate, which reacts with baking soda once it is wet and heat is applied, for example putting pancake batter on the griddle. These two reactions produce the same results but at different periods in baking. This is why baking powder is often dubbed "double-acting" and is used when leavening over an extended period is preferable, where baking soda is used when quick, one-stage leavening is desired.
When either reaction takes place, the product is carbon dioxide, or CO2, a colorless, odorless, tasteless gas. The flour combined with the liquids in the pancakes forms an elastic and sticky dough structure and this traps the CO2 as it is released. This causes small pockets to form within the dough and these bubbles inflate the pancake, creating a light fluffy texture.
During our experiment, my group also learned one more important thing: never use too much baking powder. Acids and bases have strong and often unpleasant flavors, like vinegar, and should be used in quantities too small to taste. Our largest test (unfortunately) contained one whole tablespoon for four small pancakes and tasted horrible. The key to a good pancake is not a lot of baking powder, but the right amount to make it fluffy without leaving an aftertaste. Once my group understood this we went back and made one more batch of pancakes, with just the right amount of baking powder. They were delicious.